Facet Opel

Linux comes with Fortran compilers on the CD.

Good to know, but none of my work-critical apps are available for Linux, so that pretty much kills that for me. Thanks for the info, however.

Ahhhh the Ever elusive Facet Opel. Sadly there was only ever 1 built, designed by a young man called Scott Winton, who sadly died flying the Opel when performing a forced landing at his parents property not far from where i am now.

Scott Winton Designed and built 3 aircraft, the Winton Sportsman, the Sapphire of which i owned, and the Opel. and being a Sapphire owner, i am very interested in the Opel. Sadly the Drawings and Moulds for the Opel are held by Scott Wintons parents, and they have vowed to never sell the drawing or moulds.

I have a video of a story done on the Opel on its record breaking flights. though not on my PC, i have to figure out to get the video from tape to the computer.

The Cockpit is based on the Sapphire.

Sapphire is here



The aircraft still holds the time to Altitude record in OZ, the Max Altitude by a homebuilt in OZ, the longest range of a homebuilt and the Highest speed for engine capacity.

Cruise is 150 Kts
Range of 3000 Nm

Climb
6 mins to 15,000
20 Mins to 20,000
Max alt 30,100 ft.

engine was a 447 Rotax. (40Hp)

The aircraft crashed after the prop shaft bearing failed through the rear spar, the extreme heat caused by the failed bearing caused the rear spar to fail, though he remained in control and made a forced landing and sadly the aircraft collided head on with a tree in the final stages of the rollout with caused fatal injuries to Scott.

Thanks, CriCriOz, for that really interesting stuff! I've been trying to locate information on this airplane for literally years now, with little success. I'd love to see that video, if you have a means to post it. Yours is the first detailed account of the crash that I've heard. Other postings on the web suggested a complete spar failure and departure of a wing from the aircraft. I take it the airplane had a short drive shaft that passed through the rear spar? I wasn't sure where exactly the engine was, based upon the few available photographs. The rear deck seemed a little low for a direct-drive from the Rotax, but the available perspectives aren't at at good angle to be sure.

I'd been working on an aircraft that's very broadly similar to the Facet Opel for some time, but had put it aside a few months ago. I've been considering restarting that project after some discussion I've had on this board and some further research I've done on my own.

I can certainly understand the Winton's sentiments in not wanting to release detailed plans for their son's aircraft that might see it replicated. Myself, I'd be satisfied with a good three-view and a general inboard profile. I'm not looking to build a Facet Opel - I want two seats, for one thing - but given the relative success Scott Winton had with this aircraft, I'd be interested in seeing the overall arrangement of his design, as an aid to my own project. Do you know of any source for that sort of more general information?

Thanks,

Marc

i had been after info on the opel for years also, i only found the video after seeing a picture of it on a video cover at the lovcal Ultralight and homebuilt flyin (Natlfy) our equivelent of OshKosh. i talk to the maker of the vid and he told me of the situation of the drawing and moulds. personally i think his parents should release the aircraft to be rebuilt and modified to prevent the same failure such as the rear spar to be made of heat resistant resins and carbon fibre as opposed to structural glass. and to see it become a sucessful aircraft, which will Honor the designer. but i can understand their point as well.

The "crash" was survivable, but fate interviened and he impacted a tree head on, the Opel had an undercarriage track of only about 20 inches! and it was very unstable on the ground, rocking side to side bouncing the wingtips on the ground till lift evened out the forces and it became stable. the reverse was true on landing.

The engine was directly mounted behind the cockpit aft of the forward spar,and the final drive going through the rear spar.

as soon as i can get a video capture card i will put the video up on the web.

Okay, I'm getting the 'bug' again for a design like this. I blame all of you.

Overcoming the limitations of my earlier version requires (amongst other things) removable wings. With the wings coming off for trailering, I'm rethinking having the verticals out at the wing tips. Inboard verticals (as in the Facet Opal) would be lighter, structurally more simple, and wouldn't require breaking the yaw controls when removing the wings.

But...

Orion, I've reread your post regarding the position of the vertical tails on the Freebird Extreme, which are much in the same position relative to the wing, pod, and prop as the Facet Opal. I'm concerned about the ramifications of that, in terms of reduced yaw stability/control power - an area in which a flying wing/flying plank is already 'challenged' in the first place.

I can do the basic calculations for required vertical area in a conventional airplane, but how do I account for the effect of dual verticals and a prop between? Obviously the verticals will be larger, but the question becomes: How much larger? The 'big picture' question answered as a result is whether or not it's even worth it - do the verticals become so absurdly large as to nullify the weight savings and simplicity benefits over having them at the tips?

For my performance specs and baseline engine, I've calculated a 57" prop diameter. If the verticals are at the outboard extent of the center section of the wing - and so just under 8' apart - that means the tips of the prop are only about eighteen inches from the inboard sides of the verticals. That's less than half the prop diameter.

My gut says "too close," but I'd like to put real numbers to it somehow, even if they're 'ballpark' at this point. If they're not overly large, I'd sure like to keep the verticals inboard for all the 'good' reasons stated earlier.

Ahh, the joys of design tradeoffs.

The 18" distance from the blade tips should be OK but yes, some of the issues of the Freebird do apply. The Facet Opal actually did it right in that although the verticals were in the vicility of the prop, they were not forming a tunnel along side a body so even though he did get a bit of the effect of the prop blast (decreasing autamatic sensitivity and correction to yaw), the verticals' exposure to free air still made them work.

The issue of sizing can be a tricky one but the simplest is to cut out a silohuette of your airplane (side view including the projected veertical area), locate your aft-most CG and balance the silohuette there. If it falls off nose down then you don't have enough vertical. You want it to fall of on the aft end. Then use that vertical geometry, just build two of them. This is a bit conservative but it works.

Regarding position, I tend to prefer to see the verticals located relatively inboard rather than at the tips. This is especially true in the case of a planck design.

Heh. We used to use that 'cardboard silhouette' trick for model rockets back when I was a kid. I'd forgotten about that. Thanks.

Thanks also for the additional information about the Facet Opal vs. the Freebird Extreme. I see the difference now.

Interesting about the general position of the verticals. Why do you favor having them inboard?

I think mostly that this is one of those personal preference areas that is based on a bit of data I got some time back, but never really investigated beyond the source to put it into more technical or precise terms. If I recall right, the info came from Walt Mooney, early on in my career. Since I also tend to like airplanes that result in a layout that has that "look" (like on the Opal), I've sort of latched on the brief explanation I got and never went back to really investigate the application.

A simple case - if you're slipping in yaw, one wing tip is of course forward of the other. In a planck layout this means that one of the tips looses effectiveness by moving closer to the CG w.r.t. the slipstream. Yes, the other gains a bit by being positioned a bit further aft relative to the slipstream but if you have optimized verticals, they may be too small to provide you with sufficient stability since one may essentially go away. By placing them more inboard, their relative position does not change as much as the airplane maneuvers (one reason I tend to design the size for one, but still use two).

On swept wings, like on a VariEze, this positional difference is not that significant but on a planck design there is a bit of control authority loss.

Ok, that's a really bad explanation and there is a bit more to it but I'm rather short on time and I'd have to dig out my references to make any more sense here. Sorry.

Interesting. Thanks. I think I get the gist. And no worries or apologies necessary - I appreciate all the time you give to share your experience and knowledge.

Marc

I too am very interested in Facet Opal and have some information to add. This information is a transcript from an email exchange I had with Kirk Sutton (an Aussi living in London), who knew Scott Winston and his dad.


The questions were mine, Kirk provided the answers below:

-- start of transcript --


>What I find so intriguing about Facet Opal - besides the stunning looks -
>is the fact that it obviously was able to excell in a wide range of record
>types, meaning that the concept must be intrinsically very all-round.

Not quite - it was not a pleasant plane to fly at low speed - it was much more stable at speed. In the lower speed ranges the pitch sensitivity and responses were not pleaseant. Please note I never flew the plane these are Scotts comments.


>materials improved a lot, I'm looking into ways to create a light single
>seater, that potentially could be registered as an ultra-light _and_ as a
>normal experimental.

Unfortunately you will not improve on what the facet was built on unless you go to hight temp prepreg composites! The spars were carbon fibre and kevlar in derekane (Dow wet layup vinylester) - the foam cores are klegecell for bulkheads (only 2 in the fuselage) and nomex honeycomb for the wing skins.
The skins were kevlar in derekane. The engine was a basic R447 but was fitted with a suplemental oxygine system for altitude operations.

Short of making up female moulds and doing it in high temp composites you will not improve on the basic materials in the facet.

Note - the facet cost over $120,000 in 1985 - this was why it was a
sponsored aircraft it needed to be.


>Since planks potentially have a low part count, building one should be
>easier than a conventional configuration, since there's simply less to
>build.

Absolutely, their parts count is low - it's all in the flying qualities really.


> did Scott indeed fly a single configurations for all record flights?

Yes. It flew in two configurations - initial flight with fixed
undercarriage, no vertical fins at all and non-altitude modified engine. No records were flown in this configuration it was just to prove it would fly and set the initial operating limits. The second config was with the
retract undercarriage, fins and altitude equipped engine. All records were flown in this config and the airframe was basically unpainted white all over with red tips on the fins.
After the records were flown the entire wing was then plastered with the
sponsors logos which were not painted but printed vynl stickers - these made the flight performance much worse as the airframe became really quite dirty.


>From the few pictures I could lay my hand on, one could deduce that
>perhaps the speed records were flown with a somewhat shorter wing?

No - all records on one airframe configuration - wing span was never
changed.


>- do you know anything specific about the wing section(s) used by Scott?

Yes, 1 section for the entire wing - but as the handling performance of this section at low speed was so bad Scott asked me not to pass it on as he did not want it to be used in any copies - i respect his wish. NB - it was not the NACA 63-1-A015 used on the scale model.

As far as the airframe was built see comments above.

-- end of transcript --


If anyone can come up with more information, please let me know!

AT LAST, I found one of my photos!
I've been looking for this (and I think two other) picture of the Opel I took many years back, I hope if I find the others I'll get the negatives!
Meanwhile I've been followinig this thread with interest, and feel I need to make a few comments and corrections.
The three aircraft Scott created were the 'SAPPHIRE', the 'OPEL' and the 'ULTRABAT'
I'm fairly sure the 'Winton Sportsman' was an outgrowth of his father's original 'GRASS-HOPPER'
Scott's father, Colin (Col for short) began building in the very beginning of Australian ultralighthing.
His first machine was the said Grass-Hopper, a pod and boom style machine with a mid mounted wire braced wing (ah'lah Ryan STM) with a pylon mounted pusher engine.
Col then produced the cricket using the Grass-Hopper wings on a Demosille styled body.
I have the feeling that eventually Scott and his father did not agree on some aspects, so Scott set off on his own and designed the 'SAPPHIRE'.
Originally powered by a Rotax 277 with fabric covered wings, the 'SAPPHIRE' fit into the then 95:10 regulations (400lb AUW!).
With eventual weight increases in the regulations, the 'SAPPHIRE' moved up to a 377, and then to a 447, while gaining an all glass wing with flaps.
The 'SAPPHIRE' is a delightful thing to fly if not a bit sensitive, which led many people to be caught doing aerobatics in them.
To that end, the 'ULTRABAT' was created and registered in the GA catagory to do aerobatics.
Then came the 'OPEL', where Scott intended to put Australia on the map with some serious records.
I remember speaking with Scott the first (and only) time I saw the 'OPEL' and asked how he could fly a basically non- reflexed symmetrical plank with out having to hold the elevons up all the time, to which he answered that with a small amount of 'bi-convex' in the section, plus a fairly rearward CofG, it just flew!
He also tried to explain that the fins had some form of stabilizing effect, but it all left me a bit concerned.
As for the accident, while I haven't read anything official, the story I've alway heard was that the 'OPEL' suffered an in flight structural failure at high speed and low altitude.
Rumours abound as to the cause of the failure, some say his speed attempts were done using methanol as the fuel which then attacked the structure of his wet wings.
Others say that on the high altitude flights, moisture within the layed up structure froze and expanded causing microcracking thoughout the airframe which when coupled with his more than flamboyent flying habbits, led to fatigue and eventual failure.
Truly a sad end for a young man that was destined to create some outstanding aircraft had he lived.
Arthur.

Pylon500,

your information about the 'somewhat rearward CG position' is consistent with the lacking slow speed stability behaviour that Kirk described to me....

Also note that with most sections, the Cp wanders slightly forward with higher AoA's/Cl's, which again would be consistent with the more stable high speed flight that Kirk described to me.

Hey, thanks to all for the simply wonderful information - and a very enlightening new photo of the aircraft! Definitely elevons on those wings, rather than separate elevators and ailerons.

If I read correctly, he was flying an airfoil that was either symetrical, or very slightly reflexed, and flying the aircraft at or near the neutral point?

Wow. I imagine that the flight characteristics were rather "interesting."

Thanks again to both of you. I need to digest all of this and I'll probably have questions later.

Marc

he was flying an airfoil that was either symetrical, or very slightly reflexed

The impression I got was NO reflex at all!
I do note however, that the elevons are hanging UP slightly in the photo, which could mean either, over mass balanced controls (not sure) or a spring trim system (more likely) showing that it actually flew with the elevons held up a little.
Hey I found the other photos!
These were all taken in my earlier days of photography were if I saw something of interest, I just shot it, without thought of contrast or background clutter!
Enjoy,
Arthur.